FIG. 1 is a top front perspective view of a new design for a pivot fan base;
FIG. 2 is a front elevation view thereof;
FIG. 3 is an enlarged right elevation view thereof with the fan rotated ninety degrees;
FIG. 4 is a greatly enlarged top plan view thereof;
FIG. 5 is a greatly enlarged bottom plan view thereof;
FIG. 6 is an enlarged left elevation view thereof with the fan rotated ninety degrees; and,
FIG. 7 is an enlarged rear perspective view thereof.
The broken line showing of a fan grill, a handle, decorative members on the fan hub, fan blades, and the fan motor is included for the purpose of illustrating environmental structure and forms no part of the claimed design.